IPhone 4, iPhone 4S Slide-On Macro Lens

When I couldn't find a macro lens for the iPhone 4 that had decent quality for less than $60, I designed a slide-on lens holder that can be printed out at Shapeways: http://www.shapeways.com/model/328790/

It takes a 12mm glass lens that can be bought from Surplus Shed (http://www.surplusshed.com/) for $4 - part number L4471. That was the cheapest place I could find for glass lenses.

The lens drops into a recess in the holder and is held in place by a tiny bit of superglue or similar. if you get glue on the lens, it can be cleaned off with nail polish remover or acetone. The lens I used is plano-convex (one side is flat). When inserted in the holder, the flat side of the lens faces the phone.

I also should note that you need to remove the iPhone's case, if it has one, to use this.

I ordered this one from shapeways several months ago and took lots of great macro shots with it. I've almost dropped my phone a few times which scares me - since I have to take it out of the case to use this perfectly-fitting 3D printed object... so here's my question:

I've got a 4S with a Spigen Linear Color case AND the Spigen GLAS.t film (which is pretty thick, since it's made of real tempered glass) on the front.

So - I'd need to make a modified version of your great design... I'd like to do some other mods to it to make the lens easier to clean, too - but wondering how you get the exact measurements just so. Do I use a micrometer? Do you have a recommended brand or method?

What software did you use to submit your design to shapeways (I'm inexperienced in 3D modeling)?

And finally - is there a formula for which you decided the right lens for macro (ie - would there be other lens options for making an even closer macro?) ?

Thank you! This is the first instructable I've ever done and I've taken dozens of cool shots w/ it that I've used on projectnoah.org of insects, etc.

I just measured the phone the best I could, and made 3 or 4 iterations before I got the fit right. I had an especially hard time getting up to speed on any of the normal CAD programs, so I did this on Sketch-up. It's not the best for this sort of thing, but even Autodesk 123D, which was *supposed* to be simple, just made me pull my hair. I've been told that the software sold by the makers of the Cube is nice, but I haven't tried it. The problem is that the simple-to-learn design software assumes that you are playing or making 3D face scans or whatever, and consequently don't make it easy to have precise dimensions. This lens isn't complicated, but the dimensions are of course important.

You'll probably be shocked, but I don't know that much about lenses either. I arrived at my lens choice by holding various junk box lenses (I collect that sort of stuff for tinkering) in front of the camera until I got the focus I wanted. Then a friend told me how to get the focal-length by focusing a distance point source (sun or even a light-bulb more than 10 feet away) on to a sheet of paper. The distance from the paper to the lens is it's focal length. After I had that number, I bought some lenses on-line that were around that number (also a bit bigger and smaller) and picked the one I liked best. Surplus Shed seemed to have the best deal. If you find better please post it.

A shorter focal length will give you closer macro. I tried 39mm instead of 51mm. It was closer but I thought a bit harder to use, so I stuck with 51mm.

The 3D printed holder is $11 from Shapeways, and the lens is $4 from Surplus Shed. They each charge $4 or $5 for shipping so it's about $25 if you buy only one, but gets close to $15 if you buy more. Also, the lens drops to $3 for 10 or more, and Surplus Shed periodically has 30% off sales.